Where did medical science begin? Trial and error, superstition and good luck were probably the main drivers of discovery in pre-history. But, we certainly do not have to wait until the modern era, as some may imagine, to find an appreciation of the value of experimentation and personal experience over folklore.

As good a place as any to begin our search is on one summer evening in 1527, when three of the most famous physician/scientists in history came together across a gap of fourteen centuries. These were the Roman philosopher Galen, the Persian polymath Avicenna and the Swiss professor Paracelsus, pictured above.


Paracelsus, or more correctly Theophrastus Phillippus Aureolus Bombastus von Hohenheim, was a controversial and outspoken critic of ancient medical authority. His teaching methods were unorthodox, e.g. inviting the general public to his lectures, which he delivered in German rather than Latin, while wearing an alchemist’s leather apron rather than an academic gown. His medical practice was also unconventional and owed more to his travels and his personal experiences than the accepted medical books of the day. Indeed he wrote:

Wherever I went I eagerly and diligently investigated and sought after the tested and reliable arts of medicine. I went not only to the doctors but also the barbers, bathkeepers, learned physicians, women, and magicians who pursue the art of healing; I went to monasteries, to noble and common folk, to the experts and the simple.

Despite the fact that he rejected much of accepted medical knowledge in favour of personal experience through experimentation, he firmly believed in gnomes, spirits and fairies, and there is no evidence that he ever studied medicine in any formal academic institution.

In 1526, he had been appointed to the Chair of Medicine at the University of Basel, Switzerland. However, he was not a popular choice. His arrogance preceded him and many of his contemporaries found him loathsome. But, Paracelsus was undaunted, writing:

Let me tell you this: every little hair on my neck knows more than you and all your scribes, and my shoebuckles are more learned than your Galen and Avicenna, and my beard has more experience than all your high colleges.

Perhaps driven by this arrogance, Paracelsus is reputed to have committed an act of vandalism before the university on St David’s Day, 24 June 1527, when, in a show of bravado and iconoclasm, he cast the works of Galen and Avicenna into a bonfire. A year later he was thrown out of Basel and he spent his final years as an itinerant, dying in Austria in 1541.

But who were these authors, and just why did Paracelsus find them so unequal in their achievements to the accoutrements of his footwear that their books should be consigned to the bonfire?

Both Galen and Avicenna were regarded by Paracelsus’ contemporaries as twin pillars of the medical establishment and authorities in medical science and practice. They were immortalised not only by their own writings but by their many devotees who used and reused their ideas.

Galen and Avicenna

Born into a wealthy family in Pergamon (now in modern day Turkey) in 129 CE, Galen grew up in the Roman Empire at the height of its power. He was originally destined to be a politician or a philosopher. His father, however, is reported to have received instruction in a dream from the Greek god of medicine to have his son trained in the healing arts. At the age of 16, he began his studies in Pergamon, which at the time was a cultural and intellectual centre. Three years later his father died and Galen found himself suddenly independently wealthy. Using his new-found resources, he decided to travel in order to expand his medical knowledge and experience. In 157 CE at the age of 28, he returned home and was appointed to the prestigious role of physician to the gladiators. This post allowed him to expand further his knowledge of trauma and human anatomy. Four years later Galen decided to travel to Rome where he found fame and success, eventually become the personal physician of the imperial family. He continued to practice, write and move in the highest tier of Roman society until his death in around 216 CE.

Galen is thought to be the most prolific author of antiquity, producing around 600 books, of which only around one third survive. He wrote on diverse subjects including all aspects of medicine, anatomy and physiology as well as philology and philosophy, and any attempt to discuss his output can hardly do justice to its breadth and depth.

Today, Galen is often today seen as a force that held back the progress of medicine, especially because of his adherence to, and elaboration of, the Hippocratic humoral theory of disease. However, the problem was with Galen’s unquestioned authority, not with Galen himself. His thoughts on the humoral theory and even mistakes he made in his understanding of human anatomy went unchallenged for 1,400 years. But, he would have been the first to challenge his own beliefs. He wrote:

I will trust no statements until I have tested them for myself as far as it has been possible for me to put them to the test. So if anyone after me becomes, like me, fond of work and zealous for truth, let him not conclude hastily from two or three cases. Often, he will be enlightened through long experience as I have.

Although Galen placed great store in the Hippocratic writings, which were already more than 500 years old when he was studying them, he was keen not to take things at face value. Galen believed that the practice of medicine would advance through a combination of reason and experience, adding,

The surest judge of all will be experience alone, and those who abandon it and reason on any other basis not only are deceived but destroy the value of the treatise.

Almost 800 years after Galen’s death, in 980 CE, in a village near Bukhara (now in present day Uzbekistan) Abu ‘Ali al-Husayn ibn ‘Abd Allah ibn Sina was born. He was a child prodigy, who is said to have memorised the Qur’an by the age of ten, and would become known as Ibn Sina, or in the West as Avicenna, one of the most celebrated Persian physician-scientists and philosophers of Islam’s golden age. He died in 1037 CE, but his influence lived on through his writings, especially his celebrated Canon of Medicine. Avicenna’s approach to medicine owed a great deal to the teachings of Hippocrates and Galen and indeed the perpetuation of the Hippocratic and Galenic traditions of medicine into the mediaeval world are often attributed to his writings. These writings, however, not only incorporated much of Galen’s ideas, but also assimilated works from Persian, Arabian and Ayurvedic texts, as well as Avicenna’s own experience.


When Paracelsus burned the books of Galen and Avicenna it was obviously designed to be a piece of theatre consistent with his notoriously volatile personality, but it was also an attempt to turn a new page in the history of medicine. However, others before Paracelsus had already begun to write on that next page. While the middle ages are usually regarded as a dark time that would only be illuminated by the light of the renaissance, there were physicians, scientists and scholars who, despite their adherence to the authority of antiquity, could still ask important new questions.

Despite Paracelsus’ showy attempt to shake off the shackles of the past, perhaps it was not Galen and Avicenna who should have been torched. These Roman and Persian physicians had done everything they could to advance the practice of medicine and place it on a firmer evidence-based foundation. Admittedly, they were constrained by their adherence to the accepted wisdom passed down through the years (in Galen’s case he was overly adherent to Hippocrates, and Avicenna in turn, was a slave to Galen), but they both placed high value on personal experience and experimentation. It would no doubt have astonished both Galen and Avicenna if they had learned that their works had gone unchallenged for centuries, and it would almost certainly have grieved them that medicine had, as a result, become frozen in time. They had each taken ancient traditions and developed them. In their writings, we hear not just an impersonation of their predecessors, but their own distinctive voices.

What comes next in the story, then, is the steady development of scientific thinking as it is applied to the practice of medicine. First there is the questioning of authority and the search for new answers through experimentation, and then we see the emergence of a new medicine — one built increasingly upon evidence.

© Allan Gaw 2016

This is an extract from my new book, published on March 1, 2016, which is now available for from amazon:

Testing the Waters

Lessons from the History of Drug Research

What can we learn from the past that may be relevant to modern drug research?

In this book Allan Gaw shows us how the past can illuminate the present and help us understand where we are and how we have come to be here. We will start in a world, more than two thousand years ago, long before science, but where highly disciplined minds could still formulate rigorous strategies for the evaluation of new drugs. We will move forward to see the parts played by an Emperor’s physician in Ancient Rome, a Persian philosopher and a country doctor in England. We will visit the battlefields of Europe, the laboratory benches of a German drug company and see the parts played by serendipity and innovation in the development of new drugs. In the early 20th century we will see that tragedy can be the result of inadequate testing of medicines as well as being the catalyst for change. And, we will discover how the story of one sleeping tablet changed everything.

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My other books available on kindle:

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